WIP: better logging

Author: mrc0mmand

.github/workflows/build.yml

@@ -57,7 +57,7 @@ jobs:
       - name: Install dependencies
         run: |
           sudo apt -y update
-          sudo apt -y install docbook-xsl gcc libglib2.0-dev xsltproc meson clang valgrind
+          sudo apt -y install docbook-xsl gcc libglib2.0-dev libjson-glib-dev xsltproc meson clang valgrind
 
       - name: Build
         run: |
@@ -80,7 +80,7 @@ jobs:
       - name: Install dependencies
         run: |
           sudo apt -y update
-          sudo apt -y install docbook-xsl gcc libglib2.0-dev xsltproc meson lcov
+          sudo apt -y install docbook-xsl gcc libglib2.0-dev libjson-glib-dev xsltproc meson lcov
 
       - name: Build
         run: |

meson.build

@@ -8,14 +8,15 @@ project('dfuzzer', 'c',
 )
 
 libgio = dependency('gio-2.0', required : true)
+json_glib = dependency('json-glib-1.0', required : true)
 xsltproc = find_program('xsltproc', required: false)
 
 subdir('src')
 
 executable(
         'dfuzzer',
         dfuzzer_sources,
-        dependencies : [libgio],
+        dependencies : [libgio, json_glib],
         install : true
 )
 

src/dfuzzer.c

@@ -37,6 +37,8 @@
 #include "rand.h"
 #include "util.h"
 
+/* Shared global variables */
+char *df_log_dir;
 
 /** Structure containing D-Bus name, object path and interface of process */
 static struct fuzzing_target target_proc = { "", "", "" };
@@ -71,7 +73,6 @@ static char *df_execute_cmd;
   * written to a [BUS_NAME.log] file */
 static int df_full_log_flag;
 /** Path to directory containing output logs */
-static char *log_dir_name;
 static guint64 df_max_iterations = G_MAXUINT32;
 static guint64 df_min_iterations = 10;
 /** Pointer to a file for full logging  */
@@ -94,7 +95,7 @@ int main(int argc, char **argv)
         df_parse_parameters(argc, argv);
 
         if (df_full_log_flag) {
-                log_file_name = strjoina(log_dir_name, "/", target_proc.name);
+                log_file_name = strjoina(df_log_dir, "/", target_proc.name);
                 logfile = fopen(log_file_name, "a+");
                 if(!logfile) {
                         df_fail("Error opening file %s; detailed logs will not be written\n", log_file_name);
@@ -874,7 +875,7 @@ void df_parse_parameters(int argc, char **argv)
                                                 " 'L'\n", argv[0], MAXLEN - 1);
                                         exit(1);
                                 }
-                                log_dir_name = optarg;
+                                df_log_dir = optarg;
                                 df_full_log_flag = 1;
                                 break;
                         case 'x':

src/dfuzzer.h

@@ -67,6 +67,8 @@ struct suppression_item {
         char *description;
 };
 
+extern char *df_log_dir;
+
 int df_process_bus(GBusType bus_type);
 
 /**

src/fuzz.c

@@ -23,6 +23,7 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <gio/gio.h>
+#include <json-glib/json-glib.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -48,6 +49,9 @@ static char df_except_counter = 0;
 static void df_fuzz_write_log(const struct df_dbus_method *method, GVariant *value);
 static int df_exec_cmd_check(const char *cmd);
 static int df_fuzz_call_method(const struct df_dbus_method *method, GVariant *value);
+static void df_fuzz_dump_reproducer(const char *bus, const char *object, const char *interface,
+                         const char *method, const char *signature, GVariant *value,
+                         const char *type);
 
 guint64 df_get_number_of_iterations(const char *signature) {
         guint64 iterations = 0;
@@ -399,6 +403,8 @@ static int df_check_if_exited(const int pid) {
         assert(pid > 0);
 
         sprintf(proc_pid, "/proc/%d/status", pid);
+        /* FIXME: check correctly if the target responds before checking its PID,
+         *        otherwise we might miss the crash */
 
         f = fopen(proc_pid, "r");
         if (!f) {
@@ -539,6 +545,8 @@ int df_fuzz_test_method(
                 df_fuzz_write_log(method, value);
         }
 
+        df_fuzz_dump_reproducer(name, obj, intf, method->name, method->signature, value, "fail");
+
         df_fail("   reproducer: %sdfuzzer -v -n %s -o %s -i %s -t %s",
                 ansi_yellow(), name, obj, intf, method->name);
         if (buf_size_flg)
@@ -633,3 +641,74 @@ static int df_fuzz_call_method(const struct df_dbus_method *method, GVariant *va
 
         return 0;
 }
+
+static void df_fuzz_dump_reproducer(const char *bus, const char *object, const char *interface,
+                         const char *method, const char *signature, GVariant *value,
+                         const char *type)
+{
+        g_autoptr(JsonBuilder) builder = NULL;
+        g_autoptr(JsonNode) root = NULL;
+        g_autoptr(JsonGenerator) generator = NULL;
+        g_autoptr (GError) error = NULL;
+        g_autofree gchar *filename = NULL;
+
+        /* No log dir set, don't dump anything */
+        if (!df_log_dir)
+                return;
+
+        assert(bus);
+        assert(object);
+        assert(method);
+        assert(signature);
+        assert(value);
+
+        /* Generate a JSON tree
+         *
+         * Current structure:
+         *  {
+         *      "bus": <bus_name>,
+         *      "object": <object_name>,
+         *      "interface": <interface_name>,
+         *      "method": <method_name>,
+         *      "payload": {
+         *          "signature": <signature>,
+         *          "data": <serialized_gvariant>
+         *      }
+         *  }
+         */
+        builder = json_builder_new();
+        json_builder_begin_object(builder);
+
+        json_builder_set_member_name(builder, "bus");
+        json_builder_add_string_value(builder, bus);
+        json_builder_set_member_name(builder, "object");
+        json_builder_add_string_value(builder, object);
+        json_builder_set_member_name(builder, "interface");
+        json_builder_add_string_value(builder, interface);
+        json_builder_set_member_name(builder, "method");
+        json_builder_add_string_value(builder, method);
+
+        json_builder_set_member_name(builder, "payload");
+        json_builder_begin_object(builder);
+        json_builder_set_member_name(builder, "signature");
+        json_builder_add_string_value(builder, signature);
+        json_builder_set_member_name(builder, "data");
+        json_builder_add_value(builder, json_gvariant_serialize(value));
+        json_builder_end_object(builder);
+
+        json_builder_end_object(builder);
+
+        /* Serialize the whole JSON tree */
+        root = json_builder_get_root(builder);
+        generator = json_generator_new();
+        json_generator_set_root(generator, root);
+        json_generator_set_pretty(generator, TRUE);
+
+        /* Dump it into a file */
+        filename = g_strdup_printf("%s/%s-%s-%"G_GINT64_FORMAT"-%s.json", df_log_dir,
+                                   bus, method, g_get_real_time(), type);
+        if (!json_generator_to_file(generator, filename, &error))
+                df_fail("Failed to dump reproducer into file '%s': %s\n", filename, error->message);
+
+        df_fail("   Wrote the reproducer into file '%s'\n", filename);
+}